When the oven is used in a way in which the two assemblies of beams are to move articles at the same speed, it is difficult to ensure perfect synchronization between the two assemblies, because of mechanical, electronic or hydraulic imperfections, leaks in the jacks for example. This lack of synchronization results in subjecting the supports to very high forces and to displace the products during heating, which causes difficulties during removal from the oven and may even cause overlapping of these products.
To overcome this drawback it has been proposed to provide, on the one hand, means for coupling the two beam assemblies together and, on the other hand, logic control means for providing synchronized operation of the jacks. But the ovens thus constructed are complicated.